Polyamides with talc as crystallization promoter

ABSTRACT

Disclosed are injection moldable, rapidly crystallization compositions comprising (A) a linear polyamide selected from the series poly(4,4&#39;-methylenediphenylene azelamide to dodecanediamide); and (B) an amount sufficient to promote the crystallization of the linear polyamide, of a material selected from the group of (i) talc, (ii) sodium benzenesulfonate, (iii) a polyethylene ionomer, (iv) a methacrylated butadiene-styrene, and (v) a multi-phase composite interpolymer. 
     The compositions crystallize rapidly from the molten state which allows for economically attractive molding procedures including fiber production and the production of aromatic-aliphatic polyamides having a combination of excellent properties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to polyamides and is more particularly concernedwith rapidly crystallizable compositions comprising blends ofaromatic-aliphatic polyamides and crystallization promoters.

2. Description of the Prior Art

Amorphous polyamides, particularly those high in aromatic backbonecontent (for example see U.S. Pat. No. 4,072,665), while being veryuseful for molding thermoplastics and fiber formation, do suffer fromthe drawback of remaining in the amorphous form after solidifying fromthe molten state.

Generally speaking, crystallinity in polyamides is desirable not only inorder to speed up demold rates but also to maximize polymer propertiessuch as heat deflection temperature, solvent resistance, dimensionalstability, stiffness, and the like. In the case of fibers, crystallinityimproves the breaking strength (tenacity). Unfortunately, the additionalsteps normally required to achieve crystallinity, such as prolongeddemold times, annealing, etc., of parts and fibers, result in increasesin manufacturing times and higher production costs.

The art of increasing the crystallization rate for certain polymersthrough the use of specific nucleating agents or crystallizationpromoters is known. However, this art of crystallization promotion is anempirical one and the findings with one polymer system cannot, as arule, be applied to a different polymer.

For example, at page 466 of The Encyclopedia of Polymer Science andTechnology, Vol. 10, 1969, John Wiley and Sons, New York, N.Y., it isnoted that silicas are typical nucleating agents for the nylonpolyamides. Contrastingly, U.S. Pat. No. 4,323,493 discloses that aparticular class of amides (i.e. polyamide-imide) cannot be nucleatedwith silicas but can be nucleated with talc.

A variety of additives have been disclosed for accelerating thecrystallization of the polyalkylene terephthalates. For example, alkalimetal salts of higher fatty acids have been disclosed in U.S. Pat. No.4,368,286. U.S. Pat. No. 4,368,288 states that finely divided inorganicnucleants such as talc are not very efficient, and an efficient nucleantsuch as sodium benzoate causes marked degradation of polyesters (column1, lines 35 to 40) and therefore these two materials are unsuitable.This reference discloses the use of particular ionizable metal salts oforganic compounds which actually react with the polyalkyleneterephthalates in causing the enhancement of crystallization.

In contrast to U.S. Pat. No. 4,368,288 cited supra, Axelrod et al inU.S. Pat. No. 4,401,792 actually teach the use of alkali metal salts ofbenzoic acid as well as ionomers to promote the rate of crystallizationof polyalkylene terephthalates.

U.S. Pat. No. 4,404,161 discloses an injection molding process forpolyethylene terephthalate wherein about 2 to about 30 percent by weightof a multi-phase composite interpolymer is used to lower the moldingtemperature (conversely to enhance crystallization rate) of the polymer.

The series of polyamides consisting of poly(4,4'-methylenediphenyleneazelamide), poly(4,4'-methylenediphenylene sebacamide),poly(4,4'-methylenediphenylene undecanediamine), andpoly(4,4'-methylenediphenylene dodecanediamide) is well known in theart. All of these polymers solidify to the amorphous state and remainthere unless annealed or heat treated. For references to such polymerssee U.S. Pat. Nos. 2,669,556; 3,408,334; 3,640,970 and 3,651,022 and theJ. Polymer Sci. 10, Part A-1, p. 1547, 1972.

We have now discovered that compositions comprising the above amorphouspolyamides prepared by a specific process and using certain types ofcrystallization promoters described below are rapidly crystallizablefrom the molten to solid state.

The combination of properties possessed by the molded products fromthese compositions, including high temperature resistance, excellenttensile properties and heat deflection temperature (HDT) values, reducedbrittleness (improved impact strength), and, particularly, an extremelyrapid rate of crystallization, are highly unexpected.

SUMMARY OF THE INVENTION

This invention comprises blends of,

A. a linear polyamide selected from the group consisting

of poly(4,4'-methylenediphenylene azelamide),

poly(4,4'-methylenediphenylene sebacamide),

poly(4,4'-methylenediphenylene undecanediamide),

poly(4,4'-methylenediphenylene dodecanediamide), and mixtures thereof,said polyamide being characterized in that it has been prepared by thereaction of 4,4'-methylenebis(phenyl isocyanate) and the correspondingdicarboxylic acid or by the reaction of 4,4'-methylenebis(aniline) andthe corresponding dicarboxylic acid dihalide, said polyamide beingfurther characterized by an inherent viscosity of from about 0.5 toabout 1.5 determined as a 0.5 percent by weight solution inN-methylpyrrolidone containing about 4 percent by weight lithiumchloride at 30° C.; and

B. at least one material selected from the group consisting of,

(i) talc,

(ii) sodium benzenesulfonate,

(iii) polyethylene ionomers,

(iv) methacrylated butadiene-styrene polymers, and

(v) multi-phase composite interpolymers comprising:

(a) from about 25 to 95 weight percent of a first elastomeric phasepolymerized from a monomer system comprising from about 90 to 99.8percent by weight of a C₁ to C₆ alkyl acrylate, 0.1 to 5 weight percentof a cross-linking monomer, and 0.1 to 5 weight percent of agraftlinking monomer, said crosslinking monomer being apolyethylenically unsaturated monomer having a plurality of additionpolymerizable reactive groups all of which polymerize at substantiallythe same rate of reaction, and said graftlinking monomer being apolyethylenically unsaturated monomer having a plurality of additionpolymerizable reactive groups, at least one of which polymerizes at asubstantially different rate of polymerization than at least one otherof said reactive groups; and

(b) about 75 to 5 weight percent of a final, rigid thermoplastic phasewhich is polymerized in the presence of said elastomeric phase and whichis free of epoxy groups,

said material (B) being present in the blend in at least an amountsufficient to promote the crystallization of said linear polyamide (A).

The invention also comprises fibers prepared from the blends definedabove.

DETAILED DESCRIPTION OF THE INVENTION

The polyamides employed in the compositions in accordance with thepresent invention are characterized in that they have been prepared byone of the specific processes defined above both of which are well knownin the art. For typical preparative methods using the diisocyanate routesee U.S. Pat. Nos. 3,642,715; 4,061,622 and 4,094,866 whose disclosuresrelative thereto are incorporated herein by reference. Alternatively,for typical preparative methods using the diamine-dihalide route seeCondensation Polymers by P. W. Morgan, pp 190 to 193, 1965, IntersciencePublishers, New York, N.Y.; and U.S. Pat. No. 3,206,438 whose teachingrelative to the preparation of said polyamides is incorporated herein byreference.

Preferably, the polyamides employed in the present compositions arethose prepared via the diisocyanate route.

Preferred species of polyamides in accordance with the present inventionare poly(4,4'-methylenediphenylene azelamide) andpoly(4,4'-methylenediphenylene dodecanediamide).

Minor amounts (from about 2 to about 10 mole percent ) of otherrecurring polymer linkages such as other polyamide, polyether, andpolyester, can be present in the polyamides. However, the preferredpolyamides do not contain copolymer linkages of any type. Physicalmixtures of the above described polyamides can be used in accordancewith the present invention.

We have found that polyamides prepared from 4,4'-methylenebis(aniline)and one of the corresponding dicarboxylic acids above as described, forexample, by Holmer et al U.S. Pat. No. 3,651,022, will not providecompositions having properties which are comparable to the blends of thepresent invention (see Example 7 below).

The polyamides employed in the blends of the invention are furthercharacterized by a molecular weight which, advantageously, is defined byan inherent viscosity range of about 0.5 to about 1.5 and, preferably,from about 0.7 to about 1.1 as determined under the test conditionsdefined above.

The molecular weights of the polyamides are easily controlled duringtheir preparation using any of the well known techniques such as timeand temperature of polymerization, chain terminators, control of theindex of reactants, and the like.

The materials (B) set forth above promote the crystallization of thepolyamides when the blends of the invention are fused and then allowedto solidify by whatever fusion/solidification process is involvedwhether by simple melting and cooling to solidification, or in casting,extrusion, melt-spinning, or injection molding into various moldedconfigurations, and the like.

The amount of material (B) which is sufficient to initiate thecrystallization of the amorphous polyamides varies according to factorssuch as the specific material (B) which is being employed, whichpolyamide (A) is employed, and the like. The amount required in anyparticular instance can be readily determined by trial and error.Advantageously, the promoter (B) is present in proportions of from about0.1 to about 20 percent by weight based on total composition of (A) plus(B). Preferably, it is present within a range of from about 0.5 to about15 percent by weight.

When talc or sodium benzenesulfonate are the crystallization promotersthey are employed advantageously in powdered form, preferably finelydivided form. Although they can be employed within the proportionsspecified above, they will initiate the crystallization of the blendwhen employed within a range of from about 0.1 to about 5 percent byweight of the total weight of (A) plus (B), and, preferably from about0.5 to about 5 percent. Surprising is the very fast rate which both talcand sodium benzenesulfonate provide in the crystallization of thepolyamides.

A very advantageous feature of those materials (B) falling within theclassifications of (iii), (iv) and (v) set forth above is that theyfunction in the dual capacity of crystallization promoters and impactimproving agents. Accordingly, the molded compositions in accordancewith the present invention containing (iii), (iv) or (v) arecharacterized by good impact strengths characteristic of polyamideshaving amorphous structure but at the same time they have heatdeflection temperature (HDT) values characteristic of highly crystallinepolyamides, and, of course, they possess rapid demold rates.

When the material (B) is one which falls within one of the classes of(iii), (iv) or (v) it is advantageously employed within a range of fromabout 5 to about 20 percent by weight based on (A) plus (B).

The polyethylene ionomers (iii) are ionic copolymers of α-olefins andα,β-ethylenically unsaturated carboxylic acids wherein about 10 to about90 percent of the carboxylic acids are ionized by neutralization withmetal ions. For typical ionomers which can be used in accordance withthe present invention see U.S. Pat. No. 3,264,272 whose disclosure isincorporated herein by reference.

Preferred ionomers are polyethylene polymethacrylic acid copolymershaving a methacrylic content of from about 0.2 to about 25 mole percentwith a neutralizing cation of sodium or zinc.

Illustrative of the methacrylated butadiene-styrenes class (iv) ofmaterials (B) are those copolymers employed as high efficiency impactmodifiers for polyvinyl chloride polymers such as Acryloid KM-680 (seeRohm and Haas bulletin Acryloid KM-680, January, 1983).

The multi-phase composite interpolymers class (v) of materials (B) aredescribed in detail in U.S. Pat. No. 4,404,161 cited supra and thereferences cited therein, U.S. Pat. Nos. 3,808,180 and 4,096,202disclosures of which relative to said multi-phase compositeinterpolymers are hereby incorporated herein by reference.

Preferred multi-phase composite interpolymers for use in accordance withthe present invention have only two phases, the first phase comprisingabout 60 to 95 percent by weight of the interpolymer and being derivedby polymerizing a monomer system comprising (a) 95 to 99.8 percent byweight butyl acrylate, (b) 0.1 to 2.5 percent by weight butylenediacrylate as crosslinking agent, and (c) 0.1 to 2.5 percent by weightallyl methacrylate or diallyl maleate as graftlinking agent, with afinal phase of from about 40 to about 5 percent by weight polymerizedfrom about 60 to 100 percent by weight methyl methacrylate.

Preferred members of the class of materials (B) set forth above are talcand the multi-phase composite interpolymers.

The compositions in accordance with the present invention are easilyprepared by blending together the polyamide (A) and material (B) usingany convenient blending method (dry or melt) known to those skilled inthe art. For example, the two components can be dry-blended both infinely divided form in a ball mill, Wiley mill, or the like. Optionally,the dry blending can be followed by further melt compounding as in ascrew extruder, and the like. Alternatively, the components can be meltcompounded directly by feeding them into a single or twin screwextruder.

Additionally, the compositions in accordance with the present inventioncan be blended with up to about 55 weight percent, preferably up toabout 30 weight percent of a reinforcing agent, a filler, and mixturesthereof. Illustrative of reinforcing agents are inorganic and organicfibers (including strands, chopped, roving, mats, and the like) such asglass fibers, carbon fibers, poly(phenyleneisophthalamide)fibers,poly(benzamide)fibers, and the like. Preferred reinforcing agents areglass fibers.

Illustrative of fillers which can be used are talc itself, calciumcarbonate, kaolin, graphite, molybdenum disulfide (the latter two forlubricity), powdered metals such as aluminum, copper, and the like.

The preferred filler is talc. In fact, in a surprising and unexpectedfinding, talc can be used both as a crystallization promoter and afiller in accordance with the amounts specified above for fillers. Thepolymers obtained from such blends have the properties of rapidcrystallization, retention of the good polyamide physical properties andare more economically attractive by virtue of the fact that the moreexpensive polyamide is being replaced by the talc.

A most surprising, unexpected and particularly advantageous finding isthe behaviour of the blends of the invention when employed in the meltspinning of fibers. The fibers so prepared, in sharp contrast to theprior art, crystallize almost instantly after emerging from the die.This rapid crystallization eliminates the need for an annealing anddrawing step which is necessary for prior art related polyamide fibers(see J. Polymer Sci. cited supra). Preferred compositions for use in thepreparation of fibers are those wherein the material (B) is talc.

Other additives may be added to the compositions in accordance with thepresent invention. Illustratively, such additives include antioxidants,dyes, whitening agents (titanium dioxide), fire retardants, lubricants,and the like.

The compositions in accordance with the present invention provide moldedpolymers with melt temperatures equal to or greater than 275° C. Theyenjoy the good properties of amorphous aromatic-aliphatic copolyamidessuch as ease of injection moldability while at the same time having theadvantageous properties of a crystalline aromatic-aliphatic polyamide.Some of these advantageous properties have been referred to above andinclude HDT values at 264 psi in excess of 200° C. and in some casesapproximating 250° C. which is extremely high for an injection moldablepolyamide in the absence of some type of prolonged annealing process.

Because of their high crystallinity the molded articles prepared fromthe present compositions have excellent resistance to solvents andmoisture. This is particularly true of those compositions wherein thecrystallization promoter also improves the impact strength (i.e. reducesbrittleness) but still allows for good HDT values and retention ofexcellent solvent resistance of the molded polymer.

Further, the molded polymers prepared from the present compositions haveexcellent dimensional stability because of their high HDTcharacteristics.

The blends of the invention can be used in the fabrication of articlessuch as bushings, seal faces, electric insulators, compressor vanes andimpellers, pistons and piston rings, gears, thread guides, cams, brakelinings, clutch faces, abrasive articles, and the like. The fibersderived from the blends of the invention can be used in filters inhostile environments such as in smoke stacks, or as high meltingindustrial yarns, in high speed stitching operations, in construction ofheat resistant dielectric papers and the like.

The following examples describe the manner and process of making andusing the invention and set forth the best mode contemplated by theinventors of carrying out the invention but are not to be construed aslimiting.

PREPARATION 1 Poly(4,4'-methylenediphenylene azelamide)

A 2 1. resin kettle was charged with 200.05 g. (2.097 equivalents) ofpure azelaic acid, 4.78 g. (0.0168 equivalent) of stearic acid, and 900ml. of dry tetramethylenesulfone. The stirred solution was heated to230° C. and to this solution was added 1.32 g. of dimethyl phospholineoxide followed by the slow addition (2.5 hours) of a solution of 262.35g. (98.5 percent of a precalculated 2.114 equivalents) of4,4'-methylenebis(phenyl isocyanate) dissolved in 250 ml. of drytetramethylenesulfone. The remaining 1.86 g. of 4,4'-methylenebis(phenyl isocyanate) dissolved in 10 ml. of tetramethylenesulfone wasadded in five separate portions to the stirred reaction mixture at 230°C. to bring the total added isocyanate concentration level to about 1percent over stoichiometric index. The reaction solution was heated at230° C. and stirred for an hour.

The reaction solution was poured into water thereby causing theprecipitation of the polymer in the form of solid strands. The solidpolymer was chopped up in a Waring blender, collected on a suctionfilter and washed in a continuous slow stream of water for 8 hours andfinally dried at 110° C. The inherent viscosity of thepoly(4,4'-methylenediphenylene azelamide) determined at 0.5 percent byweight in N-methylpyrrolidone containing 4 percent by weight lithiumchloride at 30° C. was 1.23 for virgin polymer.

The polymer was extruded in the form of 1/8 inch rod using a BrabenderPlasti-Corder at a screw speed of 40 r.p.m. and torque less than 1000m-g (meter-grams) with all four zone temperatures set at 280° C.; therod was chopped into pellets. The inherent viscosity on the extrudedpolymer determined same as above was 1.1.

PREPARATION 2 Poly(4,4'-methylenediphenylene dodecanediamide)

A 2 1. resin kettle was charged with 220.24 g. (1.915 equivalents) ofpure 1,12-dodecanedioic acid, 4.36 g. (0.0153 equivalent) of stearicacid, and 1000 ml. of dry tetramethylenesulfone. The stirred solutionwas heated to 247° C. and to this solution was added 1.22 g. of dimethylphospholine oxide followed by the slow addition (3 hours) of 243.24 g.(1.930 equivalents) of 4,4'-methylenebis(phenyl isocyanate) dissolved in250 ml. of tetramethylenesulfone. Following the addition the reactionsolution was heated at 247° C. for 24 hours. During this 24 hour periodsamples were removed to check viscosity at intervals of 15 and 30minutes, 1, 2, 3, 19, 21, 23, and 24 hours. The inherent viscosity ofthe reaction solution determined at 30° C. ranged from a low of 0.94 atthe 15 minute mark to a maximum of 1.16 at 2 hours and finally 1.10 at24 hours.

The polymer was isolated using the same procedure set forth inPreparation 1. The inherent viscosity of the virgin polymer determinedat 0.5 percent by weight in N-methylpyrrolidone containing 4 percent byweight lithium chloride at 30° C. was 1.12.

The polymer was extruded and chopped into pellets using the sameapparatus and procedure described in Preparation 1 except that thetorque was 700 m-g and zone 1 was 270° C. with the other three zonesbeing 280° C. The inherent viscosity on the extruded polymer determinedas above described was 1.08.

EXAMPLE 1

Four compositions (A through D) in accordance with the present inventionwere prepared first as dry powder blends by thoroughly mixing thefollowing ingredients in an electrically driven rotating tumbler.

In A and B, 445.5 g. of poly(4,4'-methylenediphenylene azelamide)(prepared in accordance with Preparation 1 above) in each case wasblended with 4.5 g. of talc (supplied by Pfizer Inc. under thedesignation MP 10-52 having a maximum particle size of 10 microns) and4.5 g. of sodium benzenesulfonate respectively. In each of C and D,382.5 g. of the same polyamide material was blended with 67.5 g. of amedium molecular weight polyethylenepolymethacrylic acid polymercontaining zinc cations (supplied by DuPont under the designation Surlyn1554) and 67.5 g. of a methacrylate/butadiene/styrene copolymer(supplied by Kaneqafuchi as Kane Ace B-56) respectively.

All four blends were then extruded through a Brabender Plasti-Corder inthe form of 1/8 inch rod at a screw speed of 40 r.p.m. and torque ofabout 1000 m-g and zone temperatures of #1=275° C.; #2=275° C.; #3=280°C.; and #4=280° C. The rods were then chopped into pellets.

The four compositions were then subjected to a known test procedure fordetermining half-times (t1/2) of crystallization at four differentisothermal temperatures. The test was performed by weighing 40 mg. sizesamples of each composition into aluminum containers which were thenindividually placed in the differential scanning calorimetry (DSC) cellof a DuPont 990 Thermal Analyzer instrument. Each sample was quicklyheated to 300° C., held for 1 minute, and then the temperature quicklydropped (greater than 50° C./minute) down to one of the four isothermaltemperatures (i.e., 230° C., 235° C., 240° C. and 245° C.) beinginvestigated. The sample was held at the specified temperature and theheat capacity measured against time. The time at which the maximumexothermic crystallization event occurred is referred to as the t1/2 ofcrystallization.

The times in seconds for t1/2 for each one of the four isothermal testtemperatures is set forth in Table I compared to the values for the basepolymer containing no crystallization promoter (Control C₉) which wasextruded and chopped into pellets according to the above describedprocedure.

The much shorter crystallization times for the compositions A, B, C andD over the Control can be seen clearly, particularly at the 230° C. and235° C. test temperatures. Compositions C and D do have longer timesover the Control at the higher test temperatures of 240° C. and 245° C.but decidedly lower times at the more advantageous lower testtemperatures of 230° C. and 235° C.

                  TABLE I                                                         ______________________________________                                                half-time (t1/2) of crystallization (secs.)                           Composition                                                                             Control C.sub.9                                                                          A       B     C     D                                    ______________________________________                                        Isothermal test                                                               temp. (°C.):                                                           230       42         21.6    21.6  32.4   22.8                                235       67.2       33.6    28.8  57.6   50.4                                240       90         54      81.6  97.2  109.2                                245       252        153.6   231.6 304.8 297.6                                ______________________________________                                    

Two compositions not in accordance with the present invention wereprepared by blending separate samples of thepoly(4,4'-methylenediphenylene azelamide) with 5 percent by weight ofp-toluenesulfonanilide and diphenylsulfone respectively and extrudingeach blend similarly to the above described method. The t1/2 ofcrystallization for the two compositions were determined at the 4 testtemperatures and in every case they were longer than the times for theControl above (Table I) except for the diphenylsulfone containingcompositions tested at 230° C.

A third composition, also not in accordance with the present invention,was prepared from the same polyamide and 1 percent by weight of sodiumbenzoate. This composition did show some increase in rate ofcrystallization over the plain polymer as determined by a decrease inthe difference between its melt and recrystallization temperaturescompared with the difference for the plain polymer by DSC experiments.However, polymer decomposition was noted in the composition by DSC.

EXAMPLE 2

A composition E in accordance with the present invention was prepared byblending together 340 g. of poly(4,4'-methylenediphenylenedodecanediamine) (prepared in accordance with Preparation 2 above) and3.4 g. of talc (MP 10-52 described in Example 1). The blend was extrudedthrough the Brabender using the same conditions set forth in Example 1except that Zone #2 and Zone #4 were 280° C. and 290° C. respectivelywith a screw speed of 20 r.p.m. and torque of about 2000 m-g. Theextruded rods were chopped into pellets.

A Control C₁₂ sample containing no crystallization promoter, which wasextruded and pelletized using the above procedure, along with thecomposition E were subjected to the test described in Example 1 fordetermining t1/2 of crystallization but at isothermal test temperaturesof 225° C., 230° C., 235° C. and 240° C. The results are set forth inTable II.

                  TABLE II                                                        ______________________________________                                                     half-time (t1/2) of crystallization (secs.)                                   Control C.sub.12                                                                        E                                                      ______________________________________                                        Isothermal test                                                               temp. (°C.):                                                           225            120         44.4                                               230            157.2       62.4                                               235            325.2       174                                                240            --*         867.6                                              ______________________________________                                         *No maximum ΔH within a 17 minute period                           

The t1/2 values for E were all much lower thanControl C₁₂ and the lattersample at the 240° C. temperature did not show a maximum in the ΔHwithin a 17 minute test period.

EXAMPLE 3

Two compositions F and G in accordance with the present invention wereprepared in the following manner. In the case of F, 1050 g. ofpoly(4,4'-methylenediphenylene azelamide) prepared in accordance withPreparation 1 above was blended with 450 g. of 1/8" chopped fiberglassstrand (Dow Corning FG 497 BB), 15 g. of talc (Pfizer MP 10-52), and 15g. of Irganox 1098 antioxidant (Ciba-Geigy, Ardsley, N.Y.). Thethoroughly blended sample was extruded through the Brabender as 1/4 inchrod at a screw speed of 40 r.p.m. and torque of 1200-1500 m-g with zonetemperatures of #1=275° C.; #2=280° C.; #3=280° C.; and #4=280° C.

Composition G was prepared by the blending of 1680 g. ofpoly(4,4'-methylenediphenylene azelamide) prepared in accordance withPreparation 1, 720 g. of 1/8" chopped fiberglass strand (Dow Corning FG497 BB), 24 g. talc (Pfizer MP 10-52), and 24 g. of titanium dioxide(supplied by Glidden as R-69). The blend was extruded under the sameconditions described above for F.

Samples of each of the compositions were injection molded into 81/2 inch×1/8 inch dumbbell test bars (ASTM D638) and into 5 inch ×1/2 inch ×1/4inch flex bars (ASTM D790) using an Arburg injection molding machine.

The injection molding conditions for composition F were as follows: zonetemperatures, #1=280° C.; #2=285° C.; #3=290° C.; screw speed 130r.p.m.; injection speed 2.8 seconds; injection pressure 9000 psi;injection time 15 sec. and injection hold 55 sec.; mold oil temperaturewas about 280° F.

The injection molding conditions for composition G were virtuallyidentical to the conditions described above except that zone 2 and 3temperatures were 5° C. lower at 280° C. and 285° C. respectively andone very critical difference in the mold oil temperature which was about210° F.

Samples of the tensile and flex bars were annealed for 1 hours at 200°C.

The physical properties of the two compositions for both the unannealedand annealed (designated by the subscript A) forms of each one and thet1/2 of crystallization for F are set forth in Table III. G. isbasically the same composition as F except for the presence of thewhitening agent titanium dioxide.

From Table III it can be seen that, when the mold temperature was about280° F. with a mold holding time of about 55 seconds, HDT values of 274°C. and 247° C. at 66 and 264 psi respectively were observed for F.Annealing the molded sample (F_(A)) is not necessary as no gain in HDTcould be observed.

When the mold temperature was 210° F. as in the case of G this had theeffect of quenching the material and resulted in only a 131° C. HDT at264 psi. Annealing of the sample (F_(A)) obviously raised the HDT valuestoward the crystalline levels of sample F.

Also, the t1/2 values for F are much faster when compared with the sameControl C₉ values set forth in Table I above.

Another composition was prepared using the same ingredients andproportions set forth above for F except that the polyamide proportionwas reduced to 900 g. while the chopped glass was increased to 600 g.The composition was processed and molded almost identically to F and hadthe molded properties set forth in parenthesis after the values for F inTable III.

                  TABLE III                                                       ______________________________________                                        Composition  F         F.sub.A   G     G.sub.A                                ______________________________________                                        Physical properties:                                                          Tensile str. (psi)                                                                         21,445    20,215    14,750                                                                              --                                     (break)      (28,220)                                                         Elongation (%)                                                                             4         3.7       --    --                                                  (4.1)                                                            Tensile modulus                                                                            763,100   775,850   601,000                                                                             --                                     (psi)        (1,044,000)                                                      Flex modulus 1,108,900 1,175,100 878,800                                                                             --                                     (psi)        (1,453,750)                                                      Flex str. (psi)                                                                            31,400    26,500    22,280                                                                              --                                                  (35,960)                                                         Notched Impact.sup.1                                                                       1.71      1.43      0.96  --                                     (ft.lb./in.notch)                                                                          (2.27)                                                           Heat deflection.sup.2                                                         temp. (°C.)                                                             66 psi      274       263       --    252                                                 (274)                                                            264 psi      247       242       131   243                                                 (247)                                                            t1/2 (secs.) at (°C.)                                                  230          20.4      --        --    --                                     235          25.2      --        --    --                                     240          44.4      --        --    --                                     245          142.8     --        --    --                                     ______________________________________                                         Footnotes to Table II                                                         .sup.1 ASTM Test Method D 25656                                               .sup.2 ASTM Test Method D 64856                                          

EXAMPLE 4

The following composition H in accordance with the present inventionillustrates how a crystallization promoter may be employed both ascrystallization promoter and as a filler for the polymers.

A 630 g. sample of poly(4,4'-methylenediphenylene azelamide) prepared inaccordance with Preparation 1 was dry blended with 243 g. of talc (about27 percent by wt.), 27 g. of titanium dioxide, and 9 g. of Irganox 1098and extruded into 1/4 inch rod using the Brabender at a screw speed of40 r.p.m. and torque of about 600 m-g, and zone temperatures of #1 and#2=280° C., and #3 and #4=285° C. The rod was chopped into pellets andinjection molded into flex and test bars using the Arburg under thefollowing condition: zone temperatures, #1=272° C.; #2=275° C.; #3=275°C.; screw speed =140 r.p.m.; injection speed =3 seconds; injectionpressure =10,000 psi; injection holding time 45 seconds; mold oiltemperature about 210° F.

The physical properties of composition H and Control C₉ (molded usingsame procedure as in H) sample referred to above, each as unannealed andannealed samples, are set forth in Table IV below. Also determined werethe t1/2 values for crystallization of H in unannealed form.

The physical properties of H show clearly that a relatively high loadingof talc can be accommodated in this composition without adverse effectsoccurring.

It is noteworthy that H, even before annealing, is characterized by ahigher HDT value (120° C./264 psi) than the control (109° C./264 psi) inspite of the low molding temperature. Annealing H results in a muchhigher HDT of 201° C. over Control (annealed) of 130° C.

Even more noteworthy are the much faster t1/2 values for H compared tothe Control C₉.

                  TABLE IV                                                        ______________________________________                                        Composition  Control C.sub.9                                                                         Control C.sub.9A *                                                                       H     H.sub.A *                             ______________________________________                                        Physical Properties:                                                          Tensile str. (psi)                                                                         9890      9860       7800  --                                    Elongation (%)                                                                             5.1        3.9       3.3   --                                    Tensile modulus                                                                            284,800   307,700    450,000                                                                             --                                    (psi)                                                                         Flex modulus 370,000   357,900    663,500                                                                             --                                    Flex strength                                                                              16,390     13,890    --                                          (psi)                                                                         Notched impact                                                                             0.77       0.67      --                                          (ft.lb./in.notch)                                                             HDT temp. (°C.)                                                         66 psi      121       224.5      --    237                                   264 psi      109        130       201                                         t1/2 (secs.) at (°C.)                                                  230          42        --         18    --                                    235          67.2      --         27.6  --                                    240          90        --         57.6  --                                    245          252       --         134.4 --                                    ______________________________________                                         *Annealed at 200° C. for 1 hour.                                  

EXAMPLE 5

The following experiment describes the preparation of a fiber from acomposition I in accordance with the present invention.

The composition was prepared by blending together 850 g. of thepoly(4,4'-methylenediphenylene azelamide) described above, 8.5 g. ofIrganox 1098, 8.5 g. of talc, and 8.5 g. of titanium dioxide whitener.

The thoroughly blended mixture was extruded through a Brabender equippedwith a 60 mesh screen pack to remove any finely divided solidimpurities, using the general extruding conditions described above. Theextrudate in the form of pellets was dried in a hopper drier (NovatecInc.) for 36 hours at 110° C.

The thoroughly dried polymer was then extruded again through theBrabender which was now equipped with an 8 hole fiber die (0.5 mm each)and a take-up spool for the spun fibers. The fibers were spun at a screwspeed of 20 r.p.m. or lower, a torque of about 1100 m-g with zone 1 and2 both at 280° C. while zone 3 and 4 were set at 285° C. and 290° C.respectively.

The fibers as spun changed from the transparent amorphous form into thecompletely opaque crystalline form after emerging only about a foot fromthe die. Their highly crystalline form was confirmed by a DSC experimenton the fiber wherein a sample was heated at 20° C./min. to 300° C.(sample melted at 286° C.) and quenched by placing the container withmolten sample in dry-ice (about -60° C.) thereby ensuring that no samplecrystallization could occur upon cooling. Then the sample was rerun inthe DSC and at 173° C. there was a strong exothermic peak ofcrystallization followed by the eventual sample melt at 286° C. Incontrast to the prior art related polyamide fibers (see J. Polymer Sci.,10, Part A-1, 1972 cited supra), the present fibers do not require anannealing step to become crystalline.

EXAMPLE 6

The following compositions J and K in accordance with the presentinvention contain a crystallization promoter which also functioned inthe role of a plasticizer and gave rise to improved polymer impactstrengths.

Composition J was prepared by blending together 382.5 g. ofpoly(4,4'-methylenediphenylene azelamide) with 67.5 g. of AcryloidKM-330 in the form of a fine white powder (bulk density =0.41 g./cc.)which is a multi-phase composite interpolymer prepared usingconventional emulsion polymerization from 79.2 parts of butyl acrylate,0.4 parts of 1,3-butylene diacrylate and 0.4 parts of dialkyl maleate ina first stage, and 20 parts of methylmethacrylate in a second stage;supplied by Rohm and Hass, Philadelphia. The blend was extruded intorods using a Brabender at a screw speed of 40 r.p.m., torque of about1000 m-g with zone 1 and 2=270° C.; zone 3=275° C.; and zone 4=280° C.

The extrudate was chopped into pellets and injection molded into testbars using an Arburg at an injection pressure of 12,000 psi, injectiontime of 15 seconds, injection holding time of 35 seconds, mold oilheating temperature =200° F.; zone 1=265° C.; zone 2 and 3=275° C.

Composition K was prepared similarly except that 382.5 g. ofpoly(4,4'-methylenediphenylene dodecanediamide) was employed. Theextrusion conditions were the same as above as were the injectionmolding conditions except for a zone #4 temperature of 275° C. for theextrusion and 11,500 psi pressure for injection molding.

Control C₉ and Control₁₂ were extruded and injection molded aspreviously described and at the low mold temperature of about 200° F.The poly(4,4'-methylenediphenylene azelamide) used as the control toprepare composition J was obtained from a different polymer batchpreparation than the poly(4,4'-methylenediphenylene azelamide) employedin the compositions of previous examples. The inherent viscosity of 1.12compared to 0.94 for the previous polymer sample is reflected in themuch longer t1/2 times for the C₉ control shown in Table V compared tothe t1/2 values set forth in Table I for Control C₉.

Samples of all the above were also annealed at 200° C. for 1 hour anddesignated by A in parenthesis. The HDT and impact strength data for allthe samples is set forth in Table V with the values for the annealedsamples set forth in parenthesis.

The compositions J and K have very good HDT values while at the sametime having impact strengths, as measured by notched Izod impact values,which are at least twice the values of the corresponding annealedcontrols.

The t1/2 times of crystallization for the J composition compared to theControl C₉ show clearly how the polyacrylate resin had given rise to adramatic speeding up of the crystallization process for thepoly(4,4'-methylenediphenylene azelamide).

                  TABLE V                                                         ______________________________________                                                     Control C.sub.9                                                                         J      Control C.sub.12                                                                       K                                      Composition  (A)       (A)    (A)      (A)                                    ______________________________________                                        Physical properties:                                                          Notched impact                                                                              0.77     2.97    0.97    3.71                                   (ft.lb./in.notch)                                                                          (0.58)    (1.58)  (0.71)  (1.73)                                 HDT (°C.)                                                               66 psi      121       --     180.4    --                                                  (224.5)   (219)  (216.1)  (221)                                  264 psi      109       98     123.5    93                                                  (130)     (121)  (144.7)  (111)                                  t1/2 (secs.) at (°C.)                                                  230          105.6     48     --       --                                     235          164.4     60.6   --       --                                     240          264       61.8   --       --                                     245          722.4     223.8  --       --                                     ______________________________________                                    

EXAMPLE 7

The following comparative composition L was based on the combination oftalc and a poly(4,4'-methylenediphenylene azelamide) polymer preparedaccording to the method of U.S. Pat. No. 3,651,022 which teaches themelt condensation of 1.01 to 1.09 moles of 4,4'-methylenedianiline withthe specified dicarboxylic acid.

A 300 ml. resin kettle was charged with 50.59 g. (0.27 mole) of polymergrade azelaic acid and 50 g. (0.25 mole) of pure4,4'-methylenedianiline. The mixture was heated slowly under a steadystream of nitrogen to 165° C. while the ingredients melted and turnedcloudy and became a pale yellow solid.

The solid was then heated under a vacuum (about 0.2 mm of mercury) to290° C. The solid became soft and gradually melted at about 280° C.during slow stirring. The melt viscosity slowly increased as the waterwas removed from the melt. After two hours the melt became very viscousand began to climb the stirrer shaft. The heating was stopped and thecooled, solidified polymer was removed from the kettle.

The polymer was pulverized in a Wiley mill. It could not be dissolved inN-methylpyrrolidone containing 4 percent by weight lithium chloride.

A sample of the polymer powder was thoroughly dry blended with 1 percentby weight of talc (Pfizer MP 10-52). The blended mixture was compressionmolded into a flex bar 5 inches ×1/2 inch ×1/4 inch under 12,000 psi and285° C. mold temperature. The bar was very brittle, too brittle to allowfor any testing of properties, and showed no particular evidence ofbeing a highly crystalline strong material.

A sample of the same polyamide without the talc and molded under thesame conditions gave the same result. The test bar appeared exactly thesame as the bar with the talc and was too brittle for testing.

We claim:
 1. A composition comprising a blend of,a linear polyamideselected from the group consisting of poly(4,4'-methylenediphenyleneazelamide), poly(4,4'-methylenediphenylene sebacamide),poly(4,4'-methylenediphenylene undecanediamide),poly(4,4'-methylenediphenylene dodecanediamide), and mixtures thereof,said polyamide characterized in that it has been prepared by thereaction of 4,4'methylenebis (phenyl isocyanate) and the correspondingdicarboxylic acid or by the reaction of 4,4'-methylenebis(aniline) andthe corresponding dicarboxylic acid dihalide, said polyamide beingfurther characterized by an inherent viscosity of from about 0.5 toabout 1.5 determined as a 0.5 percent by weight solution inN-methylpyrrolidone containing about 4 percent by weight lithiumchloride at 30° C; and talc, said talc being present in an amount atleast sufficient to promote the crystallization of said linear polyamide(A).
 2. A composition according to claim 1 wherein said polyamide (A) isprepared by the reaction of 4,4'-methylenebis(phenyl isocyanate) and thecorrresponding dicarboxylic acid, said polyamide being furthercharacterized by an inherent viscosity of from about 0.7 to about 1.1determined as a 0.5 percent by weight solution in N-methylpyrrolidonecontaining about 4 percent by weight lithium chloride at 30° C.
 3. Acomposition according to claim 2 wherein said talc is present in a rangeof from about 0.1 to about 5 percent by weight of (A) plus (B).
 4. Acomposition according to claim 3 wherein (A) ispoly(4,4'-methylenediphenylene azelamide).
 5. A composition according toclaim 3 wherein (A) is poly(4,4'-methylenediphenylene dodecanediamide).6. A composition according to claim 3 containing talc in an amount of upto about 55 percent by weight based on total weight of (A) plus (B). 7.A composition according to claim 6 wherein (A) ispoly(4,4'-methylenediphenylene azelamide).
 8. A composition according toclaim 3 which also comprises up to about 55 percent by weight offiberglass.
 9. A composition according to claim 8 wherein (A) ispoly(4,4'-methlenediphenylene azelamide).
 10. A fiber prepared from acomposition in accordance with claim 1.